Engines, including diesel engines, gasoline engines, and gaseous fuel-powered engines are used to generate mechanical, hydraulic, or electrical power. In order to accomplish this power generation, an engine typically combusts a fuel/air mixture. With the purpose of ensuring optimum combustion of the fuel/air mixture and protecting components of the engine from extreme temperatures, the temperature of the engine must be tightly controlled.
An internal combustion engine is generally fluidly connected to one or more heat exchangers to cool liquids circulated throughout the engine. These heat exchangers are often located close together, and/or close to the engine, to conserve space on the machine. An engine-driven fan may be disposed in front of the engine and heat exchanger to blow air across the heat exchanger and the engine. Alternatively, the engine-driven fan may be disposed between the engine and heat exchanger to draw air past the exchangers and blow air past the engine. The airflow removes heat from the heat exchangers and the engine.
In current engine cooling systems, a thermostat having a temperature-sensitive flow control element may be used to regulate the flow of coolant from the engine to the heat exchanger. For example, when the temperature of the engine exceeds a threshold of the thermostat, the flow control element expands to open a valve, thereby allowing communication between the engine and the heat exchanger. Since the hot coolant from the engine typically has a much higher temperature than the heat exchanger, the coolant suddenly entering the heat exchanger can cause a thermal shock that induces a strain on the heat exchanger. This strain can result in cracking of the heat exchanger, thereby shortening the lifespan of the heat exchanger and/or compromising the effectiveness of the heat exchanger.
An exemplary cooling system is described in U.S. Pat. No. 4,964,371 (the '371 patent) issued to Maeda et al. on Oct. 23, 1990. The '371 patent describes an engine cooling system comprising two temperature-regulated valves that selectively open or close a bypass passage based on coolant temperature. This mechanism allows coolant to either flow through a heat exchanger or to flow back to the engine without travelling to the heat exchanger. The opening and closing of one of the valves is additionally regulated by changes in air pressure, which vary based on changes in engine load conditions. This valve is controlled so that it closes at low engine loads regardless of temperature. In this manner, an amount of coolant passing through the heat exchanger can be varied based on engine loading.
Although the '371 patent discusses varying coolant flow dependent on changing engine load conditions, it may not adequately reduce thermal strain at all loading conditions. Specifically, the system taught in the '371 patent may still allow hot coolant returning from the engine to suddenly flow through the two valves to the heat exchanger at high engine load. Accordingly, shock loading can be experienced by the heat exchanger during operation of the engine.
The disclosed cooling system is directed to overcoming one or more of the problems set forth above and/or other problems of the prior art.